In order to assure high quality solder joints and avoid damage to sensitive electronic components during production procedures, it is important that various soldering iron operating parameters be maintained within acceptable limits. This fact has been widely recognized and has motivated the adoption of multiple standards and specifications as exemplified by Table I.
TABLE I ______________________________________ REQUIREMENTS OF VARIOUS U.S. GOVERNMENT SPECIFICATIONS Applicable Tip Tip Voltage Tip Ground Specification Temperature Potential Resistance ______________________________________ WS-6536E-2 .+-.10.degree. F. (max) .ltoreq.2 mV .ltoreq.2 ohms at idle DOD-STD- .+-.11.degree. F. (max) .ltoreq.2 mV .ltoreq.2/20 ohms 2000-1B at idle DOD-HDBK-263 No &lt;15 V &lt;20 ohms Requirement MIL-STD-45743E Control .+-.10.degree. F. &lt;2 mV N/A (max) ______________________________________
Various procedures and equipment have been developed in the prior art to determine the operating parameters of soldering irons. For example only, it has been common practice to measure soldering iron temperature by temporarily replacing the iron's working tip with a special tip having an embedded thermocouple. This procedure is both time consuming and inconvenient, and fortunately, is avoided in a soldering iron tester developed by Anritsu Meter Co. Ltd. The Anritsu model HS2D allows for the measuring of tip temperature by bringing the soldering iron working tip into substantially direct contact with a sensor in the tester. The sensor includes a thermocouple comprised of a pair of dissimilar metal wires mounted so that the junction between the wires is readily accessible for contact by the iron's working tip either directly, or preferably via a solder bead. In addition to providing a convenient means of temperature measurement, the Anritsu sensor also allows for the measurement of both leakage current and DC resistance between the iron's working tip and each of the soldering iron's two AC supply lines.
Although the Anritsu unit is very convenient to use and functions satisfactorily for its limited application, it lacks the capability to test industrial type three wire (i.e. 2 hot wires plus a ground wire) soldering irons for the more significant electrical parameters of voltage and resistance to ground. The desirability of testing for these parameters is discussed in a paper entitled "Solder-Iron Temperature Test Methods" presented by William Wahl at the China Lake Soldering Techniques Conference, China Lake, California on Aug. 18, 19 1987.